{"id":"CVE-2026-9739","revision":"fbf5b07a04b347ec811b80c701187ab5","records":[{"revision":"fbf5b07a04b347ec811b80c701187ab5","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-9739","aliases":[],"title":"Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-O…","description":"Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.","state":0,"publishedAt":"2026-05-27T21:38:55.833+00:00","modifiedAt":"2026-05-28T13:20:43.816+00:00","affected":[{"ecosystem":"Vendor product","name":"MCP Toolbox for Databases","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Google\",\n                    \"product\": \"MCP Toolbox for Databases\",\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0\",\n                            \"lessThan\": \"PR 3054 (Fix CORS bypass)\",\n                            \"versionType\": \"custom\"\n                        }\n                    ],\n                    \"defaultStatus\": \"unaffected\"\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H","score":9.4,"severity":"CRITICAL"}],"references":["https://github.com/googleapis/mcp-toolbox/issues/3053","https://github.com/googleapis/mcp-toolbox/pull/3054"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-9739","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-9739","identifiers":["CVE-2026-9739"]},"retained":false,"historicalAffected":[]}],"coverage":[]}